NEW YORK (CNNMoney.com) -- Online retailers were set to break one-day records for traffic and sales, as consumers hunted down Cyber Monday bargains.

By 2 p.m. ET, more than 300 retailing Web sites tracked by Internet monitoring firm Akamai were drawing 4.6 million visitors per minute - a three-year record for most traffic in a single day to retail Web sites.

Akamai said that its Net Usage Index - which monitors North American visitors to sites such as jcpenney.com, Bestbuy.com and Circuitcity.com - said traffic was up more than 80 percent compared to a normal Monday.

In addition, ComScore Networks estimates that Cyber Monday sales will surpass $700 million, which would make it the heaviest online spending day on record.

"Online retailers will certainly be paying close attention to what happens on Cyber Monday, which will provide an even clearer indication of what lies ahead for the rest of the season," ComScore Chairman Gian Fulgoni said in a statement.

According to the National Retail Federation (NRF), 72 million consumers plan to shop online from home or at work on one of the biggest online shopping days of the year. That's up from 61 million shoppers last year.

This year, more than 72 percent of online retailers are offering special Cyber Monday bargains and free shipping incentives, up sharply from about 43 percent last year, the trade group said.

With plenty of online discounts to bag this year, online sellers are projected to have a record-breaking sales day Monday.

Susan Phillips, vice president of marketing with online payment company Paypal, said she expects the biggest spike in traffic to happen by midday.

"This corroborates the trend we've seen in previous years that people do their Cyber Monday shopping during their lunch hour," she said.

The most sought-after deals Monday were on video games such as the Halo 3 and gaming systems like Nintendo's Wii and Sony's (Charts) PlayStation 3. Industry experts said price-conscious shoppers this year will also surf the Internet for sales on furniture, home appliances, electronics and clothing.

However, ComScore said this year's recalls of millions of toys for lead-paint hazards and faulty design will dent online toy sales, which is typically one of the hottest holiday categories.

But it was a toy that knocked Nintendo's Wii from the No. 1 spot this past weekend as the most-searched item on Yahoo! (Charts, Fortune 500) Shopping, according to Fiona Waslander, the site's director of shopping.

Wii surrendered its top spot to the Transformers Bumblebee toy, she said. "This was quite a surprise because Wii was in the top slot for most of November," Waslander added.

Wii was the second most-searched item, followed by Apple's (Charts, Fortune 500) iPhone, a Sharp Aquos 46-inch Plasma TV and the Nintendo Onyx DS Lite, which rounded out the top 5 hottest searches on Yahoo! Shopping heading into Cyber Monday, Waslander said.

Additionally, Walmart.com said its special Cyber Monday sale is the Microsoft (Charts, Fortune 500) Xbox 360 premium holiday value bundle, which includes the Xbox 360 console, an extra controller, three games and a messenger bag for less than $400.